ENERGY-GAP OF THE HIGH-T(C) SUPERCONDUCTOR HGBA2CA2CU3O8-CONTACT SPECTROSCOPY(DELTA DETERMINED BY POINT)

Tunneling spectra of a polycrystalline bulk HgBa2Ca2Cu3O8+delta with T (c) = 132 K have been measured by point-contact spectroscopy using a l ow-temperature scanning tunneling microscope. Unlike other high-T(c) s uperconductors the conductance of this material shows a BCS-like gap s tructure with a relatively small smearing parameter GAMMA. conductance s with a linear density of states for \eV\ < DELTA and a small cusp at the gap are also observed. From a simple calculation based on the ass umption that the surface is covered with a normal layer, we explained the linear dI/dV for \eV\ < DELTA and obtained two distinctively diffe rent energy gaps DELTA = 48 meV and 22 meV with the resultant 2DELTA/k (B)T(c) = 8.5 and 3.9, respectively.